Field of the Invention
The present invention relates to a substrate processing apparatus, and more particularly to a substrate processing apparatus which can perform processing, such as cleaning, of a surface (surface to be processed) of a substrate, such as a semiconductor wafer, while preventing photo-corrosion of, e.g., copper interconnects, formed in the surface of the substrate, due to exposure of the interconnects to light.
The present invention also relates to a substrate transfer method for transferring a substrate and a substrate transfer device, and more particularly to a substrate transfer method for transferring a substrate in a substrate processing apparatus and to a substrate transfer device provided in a substrate processing apparatus.
Description of the Related Art
Because of the advantages of low interconnect resistance, etc., copper is commonly used these days as an interconnect material in an electronic circuit substrate. Copper interconnects, which use copper as an interconnect material, are generally formed by carrying out copper plating of a surface of a substrate in which interconnect trenches and vias are formed, and then carrying out chemical mechanical polishing (CMP) of the substrate surface to remove an unnecessary portion of the copper plated film formed, i.e., a portion other than the copper plated film embedded in the interconnect trenches and vias.
Copper is generally weak against corrosion. Therefore, for copper interconnects formed in a substrate surface, a countermeasure against copper corrosion should be taken even during processing, such as cleaning, of the substrate surface. A copper corrosion phenomenon, called photo-corrosion, is known which occurs by the photovoltaic effect. The photo-corrosion of copper is caused when copper is exposed to light (e.g., illumination light in a clean room).
Therefore, the applicant has proposed various substrate processing apparatuses designed to prevent photo-corrosion of, e.g., copper interconnects due to exposure of a surface (surface to be processed) of a substrate to light (see Patent literatures 1 to 3). The applicant has also proposed a substrate processing apparatus which, in order to achieve a high throughput, includes a cleaning section having a plurality of cleaning lines for cleaning a plurality of substrates (see Patent literature 4).
A substrate transfer device for transferring a substrate between processing units is indispensable to a substrate processing apparatus which performs processing, such as polishing or cleaning, of a substrate. There are a variety of types of known substrate transfer devices. Among them is a widely-used substrate transfer device which has a mechanism for gripping a peripheral portion of a substrate (see Patent literatures 4 and 5).